1. Field of the Disclosure
This disclosure relates to a liquid crystal display device adapted to improve the response time of liquid crystal.
2. Description of the Related Art
Nowadays, image display devices driving pixels arranged in an active matrix shape have been widely researched. The image display devices include liquid crystal display (LCD) devices, organic electro-luminescent display (OLED) devices, and so on.
More specifically, an LCD device applies data signals, corresponding to image information, to the pixels arranged in an active matrix shape and controls the transmissivity of the liquid crystal layer so that the desired image is displayed. To this end, an LCD device includes a liquid crystal panel with the pixels arranged in an active matrix shape, and a driving circuit for driving the liquid crystal panel.
In a liquid crystal panel, gate lines and data lines are arranged to cross each other. Pixel regions are defined by the gate lines and the data lines crossing. Each of the pixel regions includes a thin film transistor (TFT) and a pixel electrode connected to it. The TFT includes a gate electrode connected to the respective gate line, a source electrode connected to the respective data line, and a drain electrode connected to the respective pixel electrode.
The driving circuit includes a gate driver sequentially applying scan signals to the gate lines and a data driver applying data signals to the data lines. As the gate driver sequentially applies the scan signals to the gate lines, the pixels on the liquid crystal panel are selected in the line unit. Whenever the gate lines are sequentially selected in a single line, the data driver applies the data signals to the data lines. As such, the transmissivity of the liquid crystal layer is controlled by an electric field which is induced between the pixel electrode and a common electrode and corresponds to the data signal applied to each pixel. Accordingly, the LCD device displays an image.
In order to lower manufacturing cost, an LCD device of an internal driver type has recently been developed which includes the gate driver and the data driver provided on the liquid crystal panel. In an LCD device of an internal driver type, the gate driver is simultaneously manufactured with the thin film transistors when the thin film transistors are formed on the liquid crystal panel. Meanwhile, the data driver may or may not be provided on the liquid crystal panel.
As the size of an LCD device increases, the gate lines lengthen by the increment of screen size so that line resistances increase. This results in the response time of the liquid crystal becoming slower due to the lowered changing rate of the thin film transistor.
An output transistor, which is positioned at an output portion applying the gate signal to the respective gate line, must be connected to a plurality of thin film transistors. Due to this, the gate signal output from the output transistor is affected by parasitic capacities within the thin film transistors. As a result, the charging rate of the thin film transistor is lowered, and furthermore the response time of the liquid crystal is deteriorated.